Purchase this article with an account.
C.A. Saito, L.C. L. Silveira, M. da Silva Filho, B.B. Lee, J.J. Kremers; Physiology of Howler Monkey Retinal Ganglion Cells: Temporal Achromatic Contrast Sensitivity . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2240.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: In primates, retinal ganglion cells of the magnocellular (MC), parvocellular (PC) and koniocellular (KC) pathways show distinct temporal sensitivity when stimulated by luminance flicker: MC cells show a contrast gain control which is absent in PC and KC cells. In the present work, we measured the temporal response of retinal ganglion cells from the howler monkey Alouatta, a trichromatic New–World primate that seems to have an opsin expression control different from other trichromatic primates. Methods: One adult male Alouatta caraja was used. Extracellular recordings were obtained from parafoveal retinal ganglion cells in vivo by tungsten–in–glass microelectrodes. We used two LEDs (554 and 638 nm), in phase, to generate sinusoidal luminance stimulation under 12 temporal frequencies, each one modulated in 11 Michelson contrasts. Retinal ganglion cells were putatively classified as MC, PC, and KC by their temporal responses to luminance pulses and to chromatic and achromatic temporal modulations. Results: Alouatta MC (n=5) cells have high response amplitude, band–pass temporal sensitivity, and response saturation accompanied by a phase advance, characteristic of a contrast gain mechanism. PC (n=2) and KC (n=1) cells were less responsive to achromatic contrast, with a low–pass temporal modulation transfer function and absence of contrast gain mechanism. Alouatta retinal ganglion cells showed a lower temporal modulation transfer function, but similar critical flicker fusion frequencies (MC: 78.12 Hz; PC: 48.07 Hz; KC: 57.47 Hz), when compared to trichromatic Cebus and Macaca. Conclusions: The results are suggestive that these three retino–geniculo–cortical pathways have many similarities in trichromatic New–World and Old–World monkeys, however displaying important quantitative differences.
This PDF is available to Subscribers Only